Such an underwater still camera is disclosed in U.S. Pat. No. 4,100,553, issued to the assignee of the present application, and comprises a watertight camera body which defines a light-tight chamber adapted to be back loaded, a lens which closes the front of the light-tight chamber and is entirely disposed outside the camera body, a shutter which is adapted to selectively cover and uncover the lens, a cocking lever which is adapted to displace the shutter to its cocked position, and a shutter release push rod which is adapted to release the shutter.
The above-mentioned U.S. patent further discloses a practical arrangement of the underwater still camera especially adapted to receive a film pack and not a single film spool or cartridge, which pack comprises in a unit not only the supply spool but also the takeup spool.
In such a still camera the camera body includes a body member and a bottom wall removably mounted thereon, and the body member is traversed by only a single transport spindle, for transporting the film.
For this purpose the transport spindle is provided with axially resiliently releasable claw means engageable with complementary claw means provided in the usual manner on the takeup spool of the pack, and an operating member, in practice a knurled head adapted to maneuver it.
Advantageously such an operating member also serves to cock the camera, in one direction of rotation it transports the film and in the opposite direction of rotation it cocks the camera, one-way rotational coupling means being provided for this purpose between the transport spindle and a cocking arm adapted to actuate the cocking lever.
It is important for the transport spindle to be held against motion in the direction of rotation corresponding to the transport of the film when the film has been transported one frame.
Accordingly the transport spindle carries crosswise inside the camera body a toothed wheel and in the body member is provided a retaining pawl which is slidably and pivotally mounted and which has at least one tooth adapted to arrestingly engage the toothed wheel under the control of means responsive to transport of the film.
In practice, in the embodiment described in the above-mentioned U.S. patent, the retaining pawl is lodged in the body member of the camera itself. The means responsive to the transport of the film comprise a tooth on the retaining pawl adapted to engage in one of the perforations which are usually provided along the longitudinal edges of such a film.
Driven by the film in the course of its transport, the retaining pawl arrests the toothed wheel of the transport spindle and therefore the transport spindle and during reverse rotation of the transport spindle for cocking the camera, the toothed wheel of the transport spindle drives the retaining pawl so that the corresponding tooth thereon is shifted into position facing another perforation of the film.